Package org.bouncycastle.crypto.modes
Class OFBBlockCipher
java.lang.Object
org.bouncycastle.crypto.DefaultMultiBlockCipher
org.bouncycastle.crypto.StreamBlockCipher
org.bouncycastle.crypto.modes.OFBBlockCipher
- All Implemented Interfaces:
BlockCipher
,MultiBlockCipher
,StreamCipher
implements a Output-FeedBack (OFB) mode on top of a simple cipher.
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprotected byte
calculateByte
(byte in) return the algorithm name and mode.int
return the block size we are operating at (in bytes).void
init
(boolean encrypting, CipherParameters params) Initialise the cipher and, possibly, the initialisation vector (IV).int
processBlock
(byte[] in, int inOff, byte[] out, int outOff) Process one block of input from the array in and write it to the out array.void
reset()
reset the feedback vector back to the IV and reset the underlying cipher.Methods inherited from class org.bouncycastle.crypto.StreamBlockCipher
getUnderlyingCipher, processBytes, returnByte
Methods inherited from class org.bouncycastle.crypto.DefaultMultiBlockCipher
getMultiBlockSize, processBlocks
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Constructor Details
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OFBBlockCipher
Basic constructor.- Parameters:
cipher
- the block cipher to be used as the basis of the feedback mode.bitBlockSize
- the block size in bits (note: a multiple of 8)
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Method Details
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init
Initialise the cipher and, possibly, the initialisation vector (IV). If an IV isn't passed as part of the parameter, the IV will be all zeros. An IV which is too short is handled in FIPS compliant fashion.- Parameters:
encrypting
- if true the cipher is initialised for encryption, if false for decryption.params
- the key and other data required by the cipher.- Throws:
IllegalArgumentException
- if the params argument is inappropriate.
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getAlgorithmName
return the algorithm name and mode.- Returns:
- the name of the underlying algorithm followed by "/OFB" and the block size in bits
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getBlockSize
public int getBlockSize()return the block size we are operating at (in bytes).- Returns:
- the block size we are operating at (in bytes).
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processBlock
public int processBlock(byte[] in, int inOff, byte[] out, int outOff) throws DataLengthException, IllegalStateException Process one block of input from the array in and write it to the out array.- Parameters:
in
- the array containing the input data.inOff
- offset into the in array the data starts at.out
- the array the output data will be copied into.outOff
- the offset into the out array the output will start at.- Returns:
- the number of bytes processed and produced.
- Throws:
DataLengthException
- if there isn't enough data in in, or space in out.IllegalStateException
- if the cipher isn't initialised.
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reset
public void reset()reset the feedback vector back to the IV and reset the underlying cipher. -
calculateByte
- Specified by:
calculateByte
in classStreamBlockCipher
- Throws:
DataLengthException
IllegalStateException
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